Research On Coordinate Strategy Of Active And Reactive Power Using STATCOM-BESS In Wind Farm

Wind power connected with grid is an important approach to the development and utilization of the large-scale wind energy. At present, the power grid peak regulated capacity in China is still relatively limited, large-scale wind power system injected into power system will bring many adverse effects to the power grid, such as reducing the voltage quality instability, leading to the frequency fluctuats, reducing system stability and so on.STATCOM is by far the most widely used static reactive power compensation device, battery energy storage system(BESS) has been widely used in the active regulating in the power system, so STATCOM and BESS are combined for the use of the wind power systems and network research. STATCOM-BESS choosed as the parallel configuration in wind farm energy storage can achieve bidirectional flow of active power and reactive power in grid, realize the four-quadrant compensation of the entire system, and support the bus voltage. The specific work of this paper is divided into four parts.Firstly, the study is made on static synchronous compensator and energy storage device to solve the problems caused by wind farms conncted to grid power, such as the main voltage source inverter working principle and application in the field. Then the combination of both devices consisting of STATCOM-BESS is analyzed, focusing on the output characteristics of STATCOM-BESS apparatus for analysis and establishing the topology of the entire system.Secondly, the mathematical model of STATCOM-BESS is derived, as the d-q coordinate transformation basing on current decoupling techniqueis adopted. This paper analysis the PI regulator parameter, converter parameters and battery capacity selection method in detail. The current decoupling control method is adopted to realize the independent regulation of active and reactive power, the coordinated control strategy of STATCOM-BESS is proposed in the operation of wind farm at the same time.Thirdly, this paper uses MATLAB/Simulink to establish the simulation model of STATCOM-BESS as the compensate device of wind farm, to verify the compensation effect of this combination device when the wind speed gradients and the wind farm output grid voltage disturbances.Fourthly, the STATCOM-BESS and the network operation verification are tested on a physical prototype, the test results show that the combination of STATCOM and BESS can be achieved between the bidirectional flow of energy in the grid and to support the network voltage and stability.